08 Nautique 211 stereo

So my friend has a 2008 air Nautique 211 team full throttle package. Boats in perfect condition but the stereo sounds like crap! Its Nautiques stock stereo which consists of 6 Polk in boat speakers, 1 12 in Polk sub and two tower speakers (actuality 4 tower speakers but two were never wired properly). The issue is that only half of the sound is playing (like if the balance was set to one side) but out of all the speakers. And when we crank it up the tower speakers will cut in and out depending how loud the song itself gets. I'm guessing that its the two amps and they are either not wired properly or not tuned correctly. Both are clarion marine amps: the large one powers the in boat speakers and sub. The smaller amp Powers the tower speakers. I'm gonna post pics of the amps and hopefully that gives you guys a picture. Thx!